Thousands of major sites are taking silent anti-ad-blocking measures

It’s no secret that ad blockers are putting a dent in advertising-based business models on the web. This has produced a range of reactions, from relatively polite whitelisting asks (TechCrunch does this) to dynamic redeployment of ads to avoid blocking. A new study finds that nearly a third of the top 10,000 sites on the web are taking ad blocking countermeasures, many silent and highly sophisticated.

Seeing the uptick in anti-ad-blocking tech, University of Iowa and UC Riverside researchers decided to perform a closer scrutiny (PDF) of major sites than had previously been done. The researchers visited thousands of sites multiple times, with and without ad-blocking software added to the browser. By comparing the final rendered code of the page for blocking browsers versus non-blocking browsers, they could see when pages changed content or noted the presence of a blocker, even if they didn’t notify the user.

The result? 30.5 percent of the top 10,000 sites on the web are using some sort of ad-blocker detection, and 38.2 percent of the top 1,000.